They are controlled by force, debt, and threat – sold into militias and marriages, lured into overseas brothels by false promises of custodial work, or bound to indentured servitude by inherited debt. The 29.8 million adults and children who live in modern slavery, according to the Global Slavery Index, are trapped by more than a lack of better options.The report details the risk and prevalence of slavery in 160 countries, including the United States, where it estimates 59,644 people are held illegally against their will. The eye-catching new numbers presented by the Australia-based Walk Free Foundation are significantly higher than previous estimates, in part because they include child brides married off to adult men.

The index, which made its debut yesterday, is part of an ambitious plan by the organization to end human slavery within a generation.

“It would be comforting to think that slavery is a relic of history, but it remains a scar on humanity on every continent," said Nick Grono, the foundation's CEO.

"Slavery in Mauritania primarily takes the form of chattel slavery, meaning that adults and children in slavery are the full property of their masters who exercise total ownership over them and their descendants. Slave status has been passed down through the generations from people originally captured during historical raids by the slave-owning groups," the report says.

"Migrants can originate from poor rural communities, lured to relatively wealthier cities by brokers on the false pretence of employment," the report finds. "Internally trafficked men, women and children make up significant shares of the workforce in construction, textiles, brick making, mines, fish and prawn processing and hospitality. However it is important to note that many of India’s enslaved have not been moved from one place to another – they are enslaved in their own villages. Many are trapped in debt bondage to a local landowner or born into slavery because of caste, customary, social and hereditary obligations."

"There's a greater sexualization of society, and a greater debasement of women. In 1990 in the UK, one in 20 men surveyed admitted that they had payed for sex. Today it's one in 10," he said.

Wilkinson welcomes the Global Slavery Index as a "clear benchmark now for future progress," even though slavery's hidden nature makes it difficult to quantify and combat. In the case of sex slavery, he said, "the women don't want to come forward because they are in fear for their lives, and they're ashamed."

Walk Free appears to have begun making its mark. Following the report's release, the Mauritanian daily C.R.I.DE.M published a searing critique of its government, which it said had not prosecuted a single person charged with enslavement since the country gained independence in 1960:

"Slavery was abolished in 1981, and even criminalized in 2007 and 2013 under the Ould Aziz regime. But each time the [Initiative for the Resurgence of the Abolitionist Movement] begins criminal proceedings, it encounters an obstruction at the very top of the government."

Earlier in the week, the European Parliament's Human Rights Subcommittee met to discuss slavery in Africa's Sahel region with an emphasis on Mauritania, though it is not clear whether this focus was related to the upcoming report. Nor is it clear whether the release of the Global Slavery Index was timed to coincide with that of "12 Years a Slave," a new film based on the 1853 autobiography of Solomon Northup, a free black man who was sold into slavery after being kidnapped in Washington, DC.

“They had been brought to Australia by their employers under false pretenses. They had their passports taken from them. They weren’t allowed to leave the house without supervision," she recounted. “It’s hard to imagine from the safety and comfort we know, yet slavery still exists in our world and in our land.”

In line with a promise to bring together business leaders and governments while raising "unprecedented levels of capital," the foundation has gathered high-profile endorsements.

It released a YouTube endorsement by former Secretary of State Hillary Clinton on Oct. 15, and claims the blessing of former British Prime Minister Tony Blair. Business magnates Richard Branson and Mo Ibrahim have given their support, and Walk Free founder Andrew "Twiggy" Forrest told Bloomberg that advice from Bill Gates had spurred him to undertake the first annual Global Slavery Index.

Forrest himself is an iron tycoon, and the wealthiest man in Australia. Walk Free is one of three large humanitarian projects belonging to Minderoo, a philanthropy and holdings company he founded with his wife, Nicola Forrest, this year, after they became the first Australasian signatories of Warren Buffet's Giving Pledge. Mr. Branson, Mr. Ibrahim, and Mr. Gates have all signed the same pledge, agreeing to donate over 50 percent of their fortunes to philanthropy.

Walk Free lays out a multiprong strategy that includes the mobilization of a "global activist movement." But it is most emphatic about forcing business leaders to stamp out slavery in their own industries.

"My senior policy man here would like to be kicking down brothels," said Mr. Forrest at the Index's Oct. 17 live streamed launch in London. "However, it's the customers that make it happen. Eliminate the customers and you'll eliminate the trade."